Avalanche Forecast
Issued: Dec 5th, 2018 4:54PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
ghelgeson,
Avalanche Canada
Cold temperatures are slowly taking some of the cohesion out of the persistent slab, but human triggering may remain possible, especially in steep unsupported alpine features.
Summary
Confidence
Low - Due to the number of field observations
Weather Forecast
This benign blocking pattern will be with us for the foreseeable future. Things begin to change on the Coast this weekend, but no precipitation is expected to make it to the Lizard Range. Unfortunately it looks like a heap of wind is coming our way Saturday night through at least Monday. WEDNESDAY NIGHT: Freezing level at valley bottom, light northwest wind, no significant precipitation expected.THURSDAY: Scattered cloud cover, freezing level at valley bottom, light southwest wind, no significant precipitation expected.FRIDAY: Clear skies, freezing level at valley bottom, light to moderate wind generally out of the west, no significant precipitation expected.SATURDAY: Scattered cloud cover, freezing level at valley bottom, light to moderate wind generally out of the west, no significant precipitation expected.
Avalanche Summary
Size 1 loose dry avalanches were reported on Wednesday from steep alpine features. No new avalanche activity to report from Monday or Tuesday.On Sunday a human triggered avalanche was reported in Cornice Bowl. We received some updated information about the size of the avalanche. It's been determined that the northwest facing feature at 2300 m produced a size 2 avalanche that ran on the early November crust. The crown was 30 to 40 cm deep, approximately 20 m wide and 300 m in length. There is a good photo in this MIN. Explosive control also triggered a few storm slabs up to size 2 from northeasterly aspects 1800-2000 m. If you're in the backcountry and have observations to share, please post to the Mountain Information Network.
Snowpack Summary
It's thin out there, check out this MIN report from our field team on Wednesday. Up to 55 cm of recent snow sits on a combination of crust and surface hoar. The crust is most prevalent at and above treeline and is likely most problematic on north facing features, especially those that are large and planar in nature.The surface hoar is tricky to pin down because it is quite spotty in distribution, but it appears to be most prevalent on sheltered slopes at and above treeline. At the bottom of the snowpack lies another crust with weak sugary facets around it. There is a great MIN Report here that provides a good visual representation of the current snowpack.At treeline the average snowpack depth is 80 cm, with only thin coverage at lower elevation.
Problems
Persistent Slabs
55 cm of old snow has been sitting in the cold temps slowly loosing cohesion. The concern is that this snow has reacted as a slab and it is resting on buried weak layers. Human triggering may remain possible, especially in steep unsupported terrain.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.Back off if you encounter signs of instability like whumphing, shooting cracks or recent avalanches.Be aware of the potential for large avalanches due to the presence of a persistent slab.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 6th, 2018 2:00PM
